Covalent organic framework with bioinspired N,S-anchored single atom sites for photocatalytic CO2 reduction reaction

Covalent organic frameworks (COFs) with bioinspired N,S-sites were constructed. Single Co atoms were coordinated with N,S-sites to create Co-THD-COF, which photocatalyzed CO2 conversion to CO with 95.1 % selectivity in water and natural seawater. The synergistic interaction between THD-COF and the single atomic Co center enhanced CO2 adsorption, activation, and reduced reaction energy barriers for *COOH intermediates, resulting in good performance. [Display omitted] •Learning from natural carbon monoxide dehydrogenase, we delicately designed a THD-COF with bioinspired N,S-coordination sites and constructed Co-THD-COF by anchoring single Co atoms on the N,S-sites.•Co-THD-COF can photocatalyze CO2 conversion to CO with 95.1 % selectivity in water and natural seawater with reusability.•Under visible light, Co-THD-COF displayed dramatically enhanced photocatalytic CO2RR activity, exhibiting the CO generating rate of 9357 μmol g−1h−1.•The synergistic interaction between THD-COF and the single atomic Co center enhanced CO2 adsorption, activation, and reduced reaction energy barriers for *COOH intermediates, resulting in good performance. Photocatalytic CO2 reduction reaction (CO2RR) has promising potential to address global energy and environmental challenges but is severely limited by sluggish kinetics and poor selectivity, where the chemical microenvironments and electronic structures of the catalytic center play pivotal roles. Herein, inspired by carbon monoxide dehydrogenase, which can accelerate CO2 to CO reduction, we delicately design a covalent organic framework (THD-COF) with bioinspired N,S-coordination sites from thiophene and imine modules on the skeleton and construct Co-THD-COF by anchoring single Co atoms on the N,S-sites. Under visible light, employing binary mixed sacrificial agents, with the help of photosensitizer [Ru(bpy)3]Cl2·6H2O, Co-THD-COF displays dramatically enhanced photocatalytic CO2RR activity, exhibiting an astounding CO generating rate of 9357 μmol g−1h−1 with the selectivity of 95.1 %. Additionally, Co-THD-COF can photocatalyze CO2 conversion smoothly in real seawater without loss of CO selectivity. Experimental and computational analysis further manifest that the single Co atom is the catalytic active center. Co-THD-COF significantly promotes CO2 adsorption and activation, charge separation dynamics, and is also beneficial to the formation of the crucial *COOH intermediates. The current study offers deep insights into the effect